CPB 69700 RESEARCH
SEMINAR
Yadvinder Singh Ahi, BVSc & AH
Graduate Student in Molecular
Virology
Thurs., April 23, 2009
VPTH 112
3:30 pm
“Characterization Of
Putative Motor Protein Of Adenovirus Assembly Process”
Abstract:
Adenovirus assembly is a multistep process that begins with the accumulation of viral structural proteins and DNA in the nucleus of infected cell. It has been proposed that adenovirus assembly proceeds through formation of empty precursor capsids followed by packaging of viral genome, similar to the assembly of bacteriophages. Recognition of the viral genome by the viral packaging machinery is dependent on the presence of a series of AT rich repeats, termed as A repeats or “the packaging domain”, located at nucleotides 194 to 358 in human adenovirus type 5 (HAd5). One of the essential components of viral assembly is a motor protein, which propels the viral genome into preformed empty capsids utilizing the chemical energy of ATP. Based on sequence analysis and experimental studies, the IVa2 protein is thought to be the motor protein of HAd5 assembly process. The IVa2 protein has been shown to interact with the packaging domain and form a multiprotein complex. Moreover, a IVa2 null virus fails to produce both empty capsids as well as the viral particles, suggesting a dual role of IVa2 in capsid assembly and viral DNA packaging. For further characterization, we expressed IVa2 protein in an E. coli system. The purified protein was used to raise hyperimmune sera in rabbits. SDS-PAGE and Western blot analyses revealed that IVa2 protein exists as a multisubunit complex in purified preparation and HAd5infected cells. IVa2 appeared in virus infected cells at 18 hours post-infection and pulse chase followed by immunoprecipitation of IVa2 protein indicated that it is a stable protein, as expected for a structural protein. Coimmunoprecipitation experiments will help to determine viral and/or cellular proteins associated with IVa2 protein.